According to a transaction process method in related arts, an I/O operation to a disk occurs during read, update and determination of data to/from a database. For this reason, there is no risk of extinguishment of updated data at server failure, while access performance to the disk becomes an upper limit of transaction process performance. Thus, processing performance cannot be improved beyond a certain extent. In addition, it is difficult to reduce a time required for restoration after system down.
In related art, a system is known in which a transaction process is performed on a memory while performing mirroring. However, there are the following problems in such a system. Restoration after server down takes time. Especially, when servers having different functions such as a server for performing data processing and a server for duplicating processed data are provided, it is necessary to store the data in the latter server once and transfer the data to the server for performing data processing and then, carry out a restoring operation, in order to restore the server for performing data processing.
Also, the restoring operation after server down is performed in the units of logical processed data. When the server is failed and 1000 pieces of the logical processed data is stored in the server, the 1000 pieces of data are restored in a restored server sequentially or for every certain piece in parallel according to the related art method. Therefore, processing depending on the 1000 pieces of data is generated, leading to a limit in processing performance.
Also, flexibility of system configuration such as a reduction in the number of servers is lack, since processing performed in a server for performing data processing is substantially symmetric with that performed in a server for duplicating processed data. Since processing performed in the server for performing data processing is also executed in the server for duplicating processed data, there is a limit in realizing a flexible system configuration, in which the server for duplicating processed data is centralized.
In conjunction with the above description, Japanese Laid Open Patent Publication (JP-P2000-57030A) discloses a client server system having database for performing double update as a related art. In this related art, the client server system has at least one client, a gateway for switching a server connected to the client, a main server and a sub-server in a same configuration and a pair of databases which are referred and updated by the main server and the sub-server. The main server and the sub-server each have an on-line application section for performing on-line processing in response to a message from the client, a database system for referring and updating the database, a message queue sending section for temporarily storing a database change message to the database of the present system and sending the message to the database of the other system, a message queue receiving section for receiving the database change message to the database of the other system and temporarily storing the message, and a message queue activating application section for inputting the database change message to the database of the other system from the message queue receiving section and updating the database of the present system via the database system. In normal operation, the main server performs on-line processing by the on-line application section, changes the main database via the main database system as necessary and sends the database change message to the main database to the main message queue sending section. In the sub-server, the sub-message queue receiving section sequentially receives the database change message to the main database from the main message queue sending section, and the sub-message queue activating application section receives input of the database change message to the main database from the sub-message queue accepting section and updates the sub-database via the sub-database system. When a damage of a file is caused in the main server, the client requesting the processing is connected to the sub-server by switching the gateway, and the sub-server performs on-line processing by the sub-on-line application section, changes the sub-database via the sub-database system as necessary and sequentially sends the database change message to the sub-database to the sub-message queue sending section. After the main server restores its function, the main message queue receiving section receives the database change message to the sub-database under processing from the sub-message queue sending section, and the main message queue activating application section inputs the database change message to the sub-database from the main message queue receiving section and updates the main database via the main database system.
Also, Japanese Laid Open Patent Publication (JP-P2003-345523A) discloses a data multiplexing system. In this related art, the data multiplexing system includes a plurality of main storage devices having at least one main storage volume and sub-storage devices which have at least one sub-storage volume, are connected to the plurality of main storage devices, and holds data in the main storage devices and the sub-storage devices in a multiplexed state by transferring sub-data containing the same contents as main data stored in the main storage volume of the main storage devices to the sub-storage devices and storing the data in the sub-storage volume of the sub-storage devices. The sub-storage device has a section for managing an arrival state of the sub-data, a section for writing the received sub-data into the sub-storage volume time-sequentially on the basis of time data added to the main data and the sub-data to represent the time when a host computer connected to the plurality of main storage devices sends the main data to each main storage device, and a section for performing state exclusion processing which excludes the arrival state of the sub-data from the main storage device from a set condition when the arrival state of the sub-data from the main storage device satisfies the set condition.
Also, Japanese Laid Open Patent Publication (JP-P2005-293315A) discloses a data mirror type cluster system. In this related art, the data mirror type cluster system includes one server which operates as a current operation system and at least one server which operates as a standby system and reflects update of data in a current operation database in the standby database. The servers are provided with databases and a shared memory which can be mutually accessed from the servers, respectively, and connected mutually via an interconnection which can transfer a transaction to the servers on the opposite sides. Each of the servers has a current operation memory driver section for writing update of data on the database into a shared memory when the database operates as the current operation system and a standby memory driver section for writing the data transferred to the shared memory via the interconnection when the database operates as the standby system.
Also, Japanese Laid Open Patent Publication (JP-A-Heisei, 4-264937) discloses an on-line database apparatus. The on-line database apparatus has a magnetic disk unit for storing data to be developed in a memory therein, a main storage unit for storing data to be accessed at high speed therein, a memory data developing section for developing data in the memory, an application interface section for accessing the memory data in accordance with an application program, an on-line control section for controlling a terminal transaction, and a memory data saving section for saving data to the magnetic disk unit at the time of the end of on-line system operation.
Also, Japanese Laid Open Patent Publication (JP-A-Heisei, 5-88954) discloses a database updating method. In this related art, the database updating method is used in a database processing system for storing a primary copy of a database in a main storage device of a processor and a backup copy of the database in a disk device. The database processing system has an updated data storage area for storing data on data updated by a transaction in the main storage device therein, a commit list for storing a transaction number which declares a commit therein, and a batch commit processing section for reflecting an update result of the translation to the primary copy in the backup copy. A transaction registers update of data of the primary copy in the update data storage area after acquiring an exclusive lock to data and registers the transaction number of the transaction itself in a commit list at a declaration of the commit. The transaction also completely releases the exclusive lock of data acquired till then. The batch commit processing section discriminates whether the transaction corresponding to the transaction number registered in the commit list can be committed or not based on data registered in the update data storage area. The batch commit processing section collectively transfers update data of a group of transactions, which can be committed, from the primary copy to a backup copy and reports the completion of commitment to the group of transactions.
Also, Japanese Laid Open Patent Publication (JP-A-Heisei, 9-244933) discloses an apparatus for backing up a database. In this related art the database backup apparatus having a main storage section in which all databases reside, and a secondary storage section for holding backup of the databases and log data. The database backup apparatus has a table for holding data in a continuous area of the main storage section in units of records, columns or a combination of the record unit and the column unit on the basis of types of data guaranteed by a recovery process and data which is not guaranteed by the recovery process, the secondary storage section for storing a table control data including position data of a record on the main storage section in a guaranteed data area and a non-guaranteed data area, a database control data including position data of a column on the main storage section in the guaranteed data area and the non-guaranteed data area and only the data guaranteed by the recovery process in the units of a record unit, a column unit or the combination of the record unit and the column unit, and a backup section for backing up only the data guaranteed by the recovery processing in the units of a record unit, a column unit or the combination of the record unit and the column unit.